Kimboman

Hi thanks ,the timber that I had in stock was 18mm marine ply and the slots were cut at 90,0 the board but this made the seat at an uncomfortable angle .

The seat does have well fitted slide in fix only but it is reinforced with 2 ribs and I changed the seat to a more horizontal position which is very comfortable and I am making a padded cushion for extra comfort ,I introduced a foot rest for the higher positions but I have also adjusted the tripod s to a smaller height to suit the chair use.

there are no retaining pins as the close fit slots and the brackets appear to be sufficient hope this helps

Hi I admired your observing  seat earlier nice job  great timber